/*
 * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * questions.
 */


package org.graalvm.compiler.nodes;

import static org.graalvm.compiler.nodeinfo.InputType.Association;
import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;

import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.Node.ValueNumberable;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.Canonicalizable;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.calc.FloatingNode;
import org.graalvm.compiler.nodes.extended.GuardingNode;
import org.graalvm.compiler.nodes.memory.MemoryKill;
import org.graalvm.compiler.nodes.spi.Proxy;
import jdk.internal.vm.compiler.word.LocationIdentity;

A proxy is inserted at loop exits for any value that is created inside the loop (i.e. was not
live on entry to the loop) and is (potentially) used after the loop.
/**
 * A proxy is inserted at loop exits for any value that is created inside the loop (i.e. was not
 * live on entry to the loop) and is (potentially) used after the loop.
 */
@NodeInfo(cycles = CYCLES_0, size = SIZE_0)
public abstract class ProxyNode extends FloatingNode implements Proxy, ValueNumberable, Canonicalizable {

    public static final NodeClass<ProxyNode> TYPE = NodeClass.create(ProxyNode.class);
    @Input(Association) LoopExitNode loopExit;

    protected ProxyNode(NodeClass<? extends ProxyNode> c, Stamp stamp, LoopExitNode proxyPoint) {
        super(c, stamp);
        assert proxyPoint != null;
        this.loopExit = proxyPoint;
    }

    public abstract ValueNode value();

    public void setProxyPoint(LoopExitNode newProxyPoint) {
        this.updateUsages(loopExit, newProxyPoint);
        this.loopExit = newProxyPoint;
    }

    public LoopExitNode proxyPoint() {
        return loopExit;
    }

    @Override
    public ValueNode getOriginalNode() {
        return value();
    }

    @Override
    public boolean verify() {
        assert !(value() instanceof ProxyNode) || ((ProxyNode) value()).loopExit != loopExit;
        return super.verify();
    }

    public static ValueProxyNode forValue(ValueNode value, LoopExitNode exit) {
        return exit.graph().unique(new ValueProxyNode(value, exit));
    }

    public static GuardProxyNode forGuard(GuardingNode value, LoopExitNode exit) {
        return exit.graph().unique(new GuardProxyNode(value, exit));
    }

    public static MemoryProxyNode forMemory(MemoryKill value, LoopExitNode exit, LocationIdentity locationIdentity) {
        return exit.graph().unique(new MemoryProxyNode(value, exit, locationIdentity));
    }

    @Override
    public Node canonical(CanonicalizerTool tool) {
        if (value() == null) {
            return null;
        }
        return this;
    }

    public abstract PhiNode createPhi(AbstractMergeNode merge);
}